I'm a whistle and accordion player who wants to move into Northumbrian piping. I play a lot of sessions, mostly English with some Irish tunes, and the tunes are mostly in G or D with the occasional foray into A or E minor. I can't work out which Northumbrian Pipe tuning to buy - G or D? My 'D' whistle will play G, Eminor and Aminor tunes, but is this an equivalent for the Northumbrian pipes? In short, what notes will a D pipe and a G pipe produce with a standard 7 key set?

I don't know anything about the English repertoire, other than the traditional NSP repertoire. For the suitability you'd have to look at the tunes you intend to play, and their range.

About traditional Irish music of course the uilleann pipes can't be beat.

There have been discussions on people trying to use Scottish Smallpipes for Irish sessions and you get into the problem of the variety of keys and ranges, resulting in needing SSP chanters in G Major, D Major, D Mix, A Mix, A Dorian, and E Dorian to be able to play a decent number of trad Irish session tunes in their usual keys.

Obviously the NSP has much more flexibility than the SSP. Still range is an issue, and I'm guessing that you would need both, G and D, to cover the keys and ranges encountered in a traditional Irish session.

My personal preference is for D NSPs. I used to play a lovely D set by Colin Ross, with a 9-key chanter, which allowed it to go down to low G. What a sound!

That would allow you to go all the way down to the lowest note a fiddle can play. But many tunes would go too high, thus the need for a G chanter as well. (You could play both chanters in the same pipes, with a split-stock arrangement.)

That is, if I understand NSP range correctly. I believe the highest note on my Ross D chanter was F#. For Irish tunes you'd have to be able to go up to B.

An NSP chanter in G would easily hit that B, the highest note usually encountered in Irish tunes.

You're correct on the range G chanter - it will give you pretty much the same range of notes as the whistle allowing you to play tunes running from D all the way up to high B. The biggest issues with a D chanter in session playing are that; you don't have a scale of G without adding more keys (and even then the G scale is not in the center) and the A scale starts right at the bottom (most A tunes will use 3 notes below this). Here's a couple of summaries for each chanter (natural scale in bold - everything else is keys)D Chanter:

(+) Allows you to play easily with musicians in G,D & A (on a 9k chanter)

(+) Tunes played in same range and without re-arrangement

(-) Narrower finger spacing can be problematic

(-) G reeds need careful selection to avoid 'harsh' tone

In terms of finger spacing - much work has been in the last 20 years by various makers with angled holes and modified bores. I have played across many sessions in the UK over the years and have multiple G chanters - but have to borrow a D chanter on the odd occasion I need one.

is the technique easier on the thumb joint with the NSP than with the UPs? I have developed a tricky bit of arthritis affecting my UP playing but I do not want to give up on piping altogether.

I would say almost certainly not. NSP are not very forgiving of arthritic thumbs - and bad posture or hand position will almost certainly exacerbate the condition.

For the left thumb there is a difference in how the thumb is held to cover the rear hole; typically more bent meaning the knuckle joint is more active. The left thumb also provides a lot of chanter support (when the right thumb is off the chanter playing the keys). The right thumb requires significantly more articulation to play all the keys, you need a high degree of movement in all three joints in the thumb.

A secondary issue is chanter balance: On a standard 7k chanter, the centre of gravity is between the two hands and the thumbs are close to the pivot. On an extended chanter (13k+) the centre of gravity moves down to the right hand or even below that, the pivot point has moved further away. This means that whenever either thumb is used, two things happen; both thumbs rotate the chanter in the same direction and the movement effect is amplified. You need much finer control of the hands to master an extended chanter.

I have both G and D NSP chanters and I would agree with all of what Rob Say stated. Playing the D set in a session is challenging because of the key work and the limited range of the upper notes in the chanter. The challenge with the G chanter is with the reed and the small finger holes. While some pipers pull it off, session speed tends to trip up my playing on the G chanter. I've heard rumor of a G chanter that has wider finger holes (mine is made by Colin Ross and sounds lovely), but I haven't played on yet.